1. Field of the Invention
This invention generally relates to lancets and blood sampling devices.
2. Prior Art
In medical laboratories, doctors' offices, and the home, there is a frequent need to draw small amounts of blood for diagnostic purposes. Usually blood samples are drawn from the finger, earlobe or another easily accessible body part of the patient. Traditionally, this is done by cleaning the surface of the patient's finger and pricking it with a lancet. Drops of blood are collected in a tube or smeared on a microscope slide for further processing.
The medical personnel or others involved in taking the sample must assure the lancet needle penetrates to an appropriate depth, both to generate enough blood sample and to avoid excessive pain or an unnecessarily large wound. It is also important to keep the lancet from pricking the finger a second time to avoid uncontrolled sampling. Additional requirements are to avoid contaminating any surface of the lancet with blood, and to prevent infection of medical personnel by blood contact. In particular, since the discovery of human immunodeficiency virus (HIV or the AIDS virus), the need to avoid contact with blood samples and lancets has become acute.
Prior lancet devices have several drawbacks. Many lancets use springs to propel the lancet tip, or a needle, into the finger of the patient. These devices do not provide precise control over the depth of penetration of the lancet. Also, many prior lancet devices do not provide for automatic retraction of the lancet tip. Instead, the user must manually retract or cover the tip to prevent re-use. Further, most prior lancet devices require separate sterile packaging to prevent contamination of the lancet tip before it is used. Examples of prior devices having these disadvantages are found in U.S. Pat. Nos. 4,539,988, 4,624,253, and 5,074,872.
This invention avoids these drawbacks of the prior art and achieves the goals described above. The invention also helps prevent infection by blood-borne pathogens, such as the AIDS virus. The invention provides a blood sampling device which is reliable, hygienic, provides an optimum prick depth, and prevents re-use, while having low production costs.